Hard to say, what yeast strain? wierd things in the beer turn out to be yeast 9 times out of 10.
My first stout was black as could be, you could not even see the yeast in the bottom. When racking to the secondary, these globs of crap floated up intermittently and slowly dissolved back down. Freaked me the %$@^ out!
Turns out it was really healthy yeast, but I still have nightmares about being in the carboy in this black beer with these huge gross things floating up from underneath. I wouldn't worry! Good Luck.